I took a piece of roofing membrane, EPDM I think they call it, but Home Depot also sells similar stuff for lining shower stalls prior to pouring concrete. Of course an old inner tube would probably work fine too. Any refrigerator is going to require ventilation for proper cooling, dissipating that heat is key. The standard vent on the left side of the cabinet, along with a built-in fan on the fridge should be adequate though.

Troy

<<I just got a 12V Isotherm fridge (nearly identical to the Vitrifrigo)
and I'm wondering if they need any sort of venting --- like the
Dometic --- or will the vent on the back of the fridge/stove cabinet
suffice? Also -  if you don't need the old external vent anymore, what
have 12V fridge owners done about the vent hole in the side of the van?

Jeff / San Anselmo>>